1. Field of the Invention
The present invention relates to a composition, a resist film, a method of forming a pattern and a method of inkjet recording. More particularly, the present invention relates to an actinic-ray- or radiation-sensitive resist composition, a resist film formed by the composition, and a method of forming a pattern using the composition. Further, the present invention relates to an actinic-ray- or radiation-sensitive or thermo-sensitive hardenable composition, a method of inkjet recording using the composition, a print, a process for producing a planographic printing plate, and a planographic printing plate.
2. Description of the Related Art
A chemical amplification photosensitive composition is a pattern forming material that is capable of, upon exposure to far ultraviolet or other radiation, generating an acid at the exposed area and, by a reaction catalyzed by the acid, changing the solubility in a developer between the area having been exposed to actinic radiation and the nonexposed area to thereby attain pattern formation on a substrate.
In the use of a KrF excimer laser as an exposure light source, a resin whose fundamental skeleton consists of a poly(hydroxystyrene) exhibiting a low absorption mainly in the region of 248 nm is employed as a major component. Accordingly, there can be attained a high sensitivity, high resolving power and favorable pattern formation. Thus, a system superior to the conventional naphthoquinone diazide/novolak resin system is realized.
On the other hand, in the use of a light source of a further shorter wavelength, for example, an ArF excimer laser (193 nm) as an exposure light source, as the compounds having an aromatic group inherently exhibit a sharp absorption in the region of 193 nm, the above-mentioned chemical amplification system has not been satisfactory.
Therefore, resists for an ArF excimer laser containing a resin with an alicyclic hydrocarbon structure have been developed.
As for photoacid generator which is a main component of a chemical amplification resist, triphenylsulfonium salt is generally known (see, for example, patent reference 1 below).
However, the known acid generators are unsatisfactory in many respects. Thus, there is a demand in the art for the development of a photosensitive composition that is enhanced in the sensitivity, resolution, pattern configuration, roughness characteristic, etc. through the improvement of such acid generators.
In particular, the roughness characteristic and resolution become serious in accordance with the reduction of pattern dimension. In the field of, for example, the lithography using X-rays, electron beams or EUV, as the formation of a fine pattern of several tens of nanometers is targeted, the demand for especially high resolution and roughness characteristic is strong.
When use is made of a light source emitting electron beams, X-rays, EUV or the like, the exposure is carried out in vacuum. This tends to cause low-boiling-point compounds, such as solvents, and resist materials decomposed by high energy to evaporate to thereby dirty the exposure apparatus. This outgas problem is becoming serious. In recent years, various researches have been made on the reduction of the outgas. Various proposals have been made, which include a proposal to inhibit the evaporation of low-molecular compounds by providing a top coat layer (see, for example, patent reference 2) and a proposal to add a radical trapping agent for the inhibition of polymer decomposition (see, for example, patent reference 3). For acid generators as well, an ingenuity for outgas reduction is demanded.
Furthermore, patent reference 4 proposes a positive photoresist composition for far-ultraviolet exposure which comprises a specified acid-decomposable resin and compound (sulfonic-acid-generating compound) that when acted on by an acid, is decomposed to thereby generate a sulfonic acid for the purpose of solving the problems of development defect, scumming, etc.
In Paragraph 0016 of patent reference 4, there is a description to the effect that as the acid generated by the sulfonic-acid-generating compound, one of high acid strength is preferred. Further, there is a description to the effect that a sulfonic acid containing an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group is preferred as the generated acid. In Paragraphs 0017 and 0018 of the reference, as preferred examples of the generated acids, there are mentioned the compounds of general formulae (1) to (5).
As an image recording system capable of forming an image on a recording medium, such as paper, in accordance with an image data signal, for example, an electrophotographic system, a sublimation or fusion thermal transfer system and an inkjet system are known. The electrophotographic system requires a process for forming an electrostatic latent image on a photoreceptor drum through electrification or exposure to thereby render the system complex with the result that the problem of high production cost or the like arises. In the thermal transfer system, the apparatus cost is low. However, as an ink ribbon is used, the problems of high running cost and waste material output arise. In contrast, in the inkjet system, the apparatus cost is low, and as an ink is jetted to only required image areas so as to carry out direct imaging on a recording medium, the ink can be efficiently used, rendering the running cost low. Further, noise is low. Therefore, the inkjet system is advantageous as an image recording system.
It is required for the ink composition for inkjet recording (radiation-hardenable ink composition) capable of being hardened when exposed to radiation, such as ultraviolet, to have satisfactorily high sensitivity and provide high image quality. Attaining high sensitivity ensures high hardenability upon exposure to radiation and thus realizes many advantages including the reduction of power consumption, the prolongation of life by the reduction of load on a radiation emitter and the prevention of the occurrence of low-molecular substances attributed to unsatisfactory hardening. Further, attaining high sensitivity, especially when the ink composition is used in image areas of a planographic printing plate, increases the strength of image areas hardened, so that an extended plate life can be realized. Such ink compositions per se are being marketed and stored under various conditions. Accordingly, it is required for the ink compositions to have a high storage stability.
An ultraviolet-hardenable resin composition comprising a cationically polymerizable compound and a photoacid is known as an overcoating agent for optical disk (see, for example, patent reference 5). It is reported that this composition realizes a relatively high hardening sensitivity (see the same reference). However, soaking on recycled paper is observed, and the storage stability of the composition is poor. Moreover, coloring is observed at the time of ink hardening, and thus the composition has the drawback that a color difference is brought about between before and after ink hardening.
Still further, it is reported to employ an ink composition in which a basic compound is contained in order to not only improve the discharge stability of ink droplets but also reduce the curling and wrinkling of recording material attributed to ink shrinkage at the time of ink hardening (see, for example, patent reference 6).    [Patent reference 1] U.S. Pat. No. 6,548,221,    [Patent reference 2] European Patent No. 1480078,    [Patent reference 3] U.S. Pat. No. 6,680,157,    [Patent reference 4] Japanese. Patent No. 3912761,    [Patent reference 5] Jpn. Pat. Appln. KOKAI Publication No. (hereinafter referred to as JP-A-) H9-183928, and    [Patent reference 6] JP-A-2003-341217.